"Many metal fans began to reciprocate the gesture and along with headbanging, it became synonymous with metal."

Less energetic than headbanging

Dio wasn't the first, says Young. In the 1960s, there had been Coven frontman Jinx Dawson, and the cartoon version of John Lennon on the cover of The Beatles' Yellow Submarine was seen using it too. But it really took off from Dio.

It has been misinterpreted as a sign of allegiance to the devil, because the shape of the fingers have been associated with 666, the number of the beast, says Young.

But Dio, says Young, explained that he was taught the so-called corna sign by his Italian grandmother, as a way to scare off the "evil eye", a look which is said to cause bad luck. It's like knocking on wood for superstitious purposes (more on this below).

Fans copied Dio because they thought it looked cool, and it became a sign of appreciation at gigs. But it has more recently crossed over into mainstream youth culture, says Young.

"Rihanna, Britney Spears and Avril Lavigne have all done it - perhaps they're all secret metal fans - but it has led to several internet groups forming in protest over the 'egregious overuse and inappropriate use' of throwing the horns. Quite right. Leave it to the metal fans."

WARDING OFF THE EVIL EYE

When Dio's Italian grandmother taught him the corna sign, she was drawing on a much older superstition.

WHO, WHAT, WHY?

A regular part of the BBC News Magazine, Who, What, Why? aims to answer some of the questions behind the headlines

Bram Stoker mentioned it in his novel Dracula, published in 1897. In the first chapter, protagonist Jonathan Harker notes the following in his journal while in Eastern Europe's Carpathian Mountains:

"When we started, the crowd round the inn door, which had by this time swelled to a considerable size, all made the sign of the cross and pointed two fingers towards me. With some difficulty I got a fellow-passenger to tell me what they meant; he would not answer at first, but on learning that I was English, he explained that it was a charm or guard against the evil eye."

This superstitious belief is especially common in Italy, but it is also shared in other countries.

In southern Italy, it can also be directed at a man whose wife is thought to be unfaithful, so it should be exercised with great care.

'GO, THE TEXAN LONGHORNS'

Go, Texas!

The slogan of the University of Texas is "Hook 'em, horns" and the hand sign that illustrates this motto is the same as the one used by heavy metal fans.

It is intended to symbolise the head and horns of the university mascot, the longhorn, and has been used since the 1950s.

Fans use it as a greeting or just to emphasise their Texan identity, a demonstration most famously seen in recent years by George W Bush.

His wife Laura and daughters were also fans.

'I LOVE YOU'

With the thumb sticking out, it has a different meaning entirely.

"It is the American sign for 'I love you'," says Sarah Murray of the British Deaf Association.

Obama used it on the campaign trail

"It would probably be recognised by people here [in the UK] but you wouldn't see it often used."

American politicians like Barack Obama, Bill Clinton and Dick Cheney have been photographed using it in the same way, although some believe that Jimmy Carter was its first exponent when running for president in the 1970s.

When the Obamas use it with their thumb sticking out, it is different from the specifically Texan use by George Bush, says Trevor McCrisken, a professor in US politics at the University of Warwick.

"They want to show that they care about people that need to use sign language," he says. "If you're at a political event in the US, there will be a couple of people down the front signing to the audience, so they're more careful [than in the UK] to ensure that everyone with special needs is catered for."

'HANG LOOSE'

It's Ronaldinho's trademark celebration

At his presidential inauguration, President Obama was seen doing what is known as the "shaka" greeting, which has the thumb and little finger extended.

It is also exercised by Brazilian footballer Ronaldhinho as part of his goal scoring celebrations.

In Hawaii, where the president was born, the sign conveys affection or "aloha".

It has been adopted by the wider surfing community as a greeting meaning "hi", "cool" or "hang loose".

Below is a selection of your comments.

Hook 'Em Horns!! A tribute to the University of Texas Mascot BEVO. A sign appreciated by few, hated by most. Due to the superiority of UT's academics and sports teams university of students around the US put them upside down in an attempt to mock the school and its die-hard fans.Alexander Dickey, Austin, Texas

When I was growing up in Canada, that hand symbol meant "The excrement of a male bovine", more commonly referred to as "BS". It was generally used by someone who didn't believe what someone else had just told them.Gordon Morrison, Basingstoke, UK

In South Africa it's used as an expression of excellence. It started as a cricketing term - "Give it Horns" ie the signal for a six. The hand gesture is just a mini version.Doug Mullins, Winchester

In Turkey, this hand gesture is adapted by the far right group Grey Wolves. This ultra fascist organisation is behind many assassins of Turkish left-wing intellectuals and "unsolved" murders since 70s and still very much active.James, London

I always thought it was an insult, the sign (horns) of the cuckold. Made by one man to another to indicate spousal infidelity.Micha, London, England

I've lived in Italy for 30 years and le corna is definitely the same as Bram Stocker's meaning to block any evil spells or evil eye since you can blind the devil by poking your little finger together with index into his eyes so that you become invisible to him and bad luck. However even worse for an Italian, le corna also means your husband/wife/partner is cheating on you... so the mixture of superstition and profound humiliation is extremely potent. You can protect yourself by carrying on your person a lucky charm of coral shaped like a horn.Chris Thomas, Milan

The so-called "shaka" (thumb and little finger extended) is also a greeting/salute used by VW drivers (superficial resemblance to the VW logo). So perhaps Ronaldinho is a secret split-screen bus or Beetle owner?Richard Cornwell, Sussex, UK

I was surprised to see this in Russia, but with the back of the hand facing outwards (and not holding them above the head). It means well off or rich - for example, while discussing houses: "Those houses are very [gesture]". The meaning is strengthened by using both hands, holding them side by side. I have no idea where it came from though.James Hazeldine, Stafford

Dio popularized it, but the late Great Frank Zappa was flashing it often, himself back in the 70s. Both men being somewhat Italian. Frank does it in Baby Snakes, and at the beginning of his stint on Make Me Laugh facing Gallegher.Titus Andronicus, Houston, USA

Somewhat oddly, you seem to have missed out the most cited answer to this question - that it is a secret society gesture. Note - not exclusively so, but that is allegedly one of its uses. Gareth Wilson, London

Reorientate the 'shaka' so it's vertical instead of horizontal, and it's also the symbol for telephone, or a phone call. DB, Amersham

The sign is commonly used in South Africa to symbolise cattle. In African culture a man's wealth was directly related to how many cattle he owned. Thus by extension it has come to symbolise good luckSteve Philpott, South Africa

In Spain, this is the cornudos [horns] sign. It represents the horns of a goat and the fact that everyone but the goat can actually see the horns. It is shown to people you wish to insult (generally driving) and means that they are being cuckolded right there and then. All the other explanations seem quite polite in comparison but there must be some connection with the Italian corno.Alan Tuthill, Heathrow

I don't know about the two horns, but I read about the two fingers - the V - is very old and comes from the days of Agincourt when the English bowmen slaughtered the French army. Those two fingers are used to place the arrow and draw the bow string back. If the French ever caught any bowmen those fingers were cut off. At subsequent battles the fingers were held up as a taunt to the FrenchChris, London

Re Chris in London talking about the English taunting the French with two fingers - please have the QI buzzer go off in your head sir. It's come to mean that, but the first reference to this wasn't until the 1970s (unless Stephen Fry is wrong, and that can't be right can it?).Simon, Alvechurch

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